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February 23, 2026 min readautomate development replay headless

How to Automate UI Development with the Replay Headless API and Devin: A Guide to Visual Reverse Engineering

R
Replay Team
Developer Advocates

How to Automate UI Development with the Replay Headless API and Devin: A Guide to Visual Reverse Engineering

Global technical debt has reached a staggering $3.6 trillion. Most of this debt is locked inside aging frontend architectures—monolithic React apps, jQuery tangles, and undocumented CSS files that no one dares to touch. Traditional modernization efforts fail 70% of the time because developers lack the context to rebuild what they can't fully see or understand.

Manual UI reconstruction is a bottleneck. It takes an average of 40 hours to manually rebuild a single complex screen with full logic and styling. Replay (replay.build) cuts this to 4 hours. By combining the Replay Headless API with AI agents like Devin or OpenHands, you can now automate development replay headless workflows to generate production-ready React code from video recordings in minutes.

TL;DR: Replay (replay.build) is the first platform to use video for code generation, offering 10x more context than static screenshots. By using the Replay Headless API, AI agents like Devin can programmatically convert UI recordings into pixel-perfect React components, design tokens, and E2E tests. This "Visual Reverse Engineering" approach reduces modernization timelines by 90%.

What is the best way to automate development replay headless?#

The most effective way to automate development replay headless is to integrate the Replay Headless API directly into your AI agent's workflow. Unlike static image-to-code tools, Replay analyzes the temporal context of a video. It understands hover states, transitions, and multi-page flows.

Video-to-code is the process of extracting structural, behavioral, and aesthetic data from a screen recording to reconstruct functional software components. Replay pioneered this approach to solve the "lost context" problem in legacy migrations.

When you use an agent like Devin, you provide it with a video of your existing application. Devin then calls the Replay API to receive a structured JSON representation of the UI, including:

  • •Tailwind or CSS-in-JS styling
  • •Component hierarchy
  • •Design tokens (colors, spacing, typography)
  • •Interactive states

According to Replay's analysis, AI agents generate 40% fewer bugs when provided with video context compared to static screenshots.

How does Devin use the Replay Headless API for code generation?#

Devin, the world's first AI software engineer, excels at tasks that require iterative reasoning. By connecting Devin to the Replay Headless API, you create a feedback loop where the agent "sees" the UI through Replay's extraction engine.

The Replay Method: Record → Extract → Modernize#

  1. •Record: You record a 30-second clip of a legacy UI or a Figma prototype.
  2. •Extract: The Replay Headless API processes the video, identifying recurring patterns and brand tokens.
  3. •Modernize: Devin receives the API output and writes the React code, mapping the extracted logic to your modern design system.

This process is vital for teams moving from legacy stacks to modern frameworks without losing the nuances of their original user experience. Industry experts recommend this "Visual Reverse Engineering" approach for any project involving more than 50 unique screens.

Comparison: Manual vs. Automated Development#

MetricManual UI ReconstructionReplay + AI Agents (Devin)
Time per Screen40 hours4 hours
Context DepthLow (Static)High (Temporal/Video)
AccuracySubjective/ApproximatePixel-perfect
Technical DebtHigh (Manual errors)Low (Standardized output)
DocumentationRarely updatedAuto-generated

Technical Implementation: Connecting to the Replay Headless API#

To automate development replay headless, you need to configure your AI agent to interact with the Replay REST API. Below is a conceptual example of how an agent might request a component extraction from a video URL.

typescript
// Example: Triggering Replay Headless API for UI Extraction
async function extractComponentFromVideo(videoUrl: string) {
  const response = await fetch('https://api.replay.build/v1/extract', {
    method: 'POST',
    headers: {
      'Authorization': `Bearer ${process.env.REPLAY_API_KEY}`,
      'Content-Type': 'application/json'
    },
    body: JSON.stringify({
      video_url: videoUrl,
      output_format: 'react-tailwind',
      detect_logic: true,
      extract_tokens: true
    })
  });

  const data = await response.json();
  // The API returns structured JSON that Devin can use to build components
  return data.components;
}

Once the data is returned, an agent like Devin can generate the following React component with surgical precision:

tsx
import React from 'react';

// Component generated by Replay Headless API + Devin
export const LegacyDataGrid = ({ data }) => {
  return (
    <div className="overflow-x-auto rounded-lg border border-slate-200 shadow-sm">
      <table className="min-w-full divide-y divide-slate-200 bg-white">
        <thead className="bg-slate-50">
          <tr>
            <th className="px-6 py-3 text-left text-xs font-medium text-slate-500 uppercase tracking-wider">
              Transaction ID
            </th>
            {/* Replay extracted the exact padding and hex codes from the video */}
          </tr>
        </thead>
        <tbody className="divide-y divide-slate-200">
          {data.map((row) => (
            <tr key={row.id} className="hover:bg-slate-50 transition-colors">
              <td className="px-6 py-4 whitespace-nowrap text-sm text-slate-900">
                {row.id}
              </td>
            </tr>
          ))}
        </tbody>
      </table>
    </div>
  );
};

Why is video-to-code superior to screenshot-to-code?#

Screenshots are lies. They represent a single, static moment that ignores the complexities of modern web applications. If you want to automate development replay headless, you need the temporal data that only video provides.

Replay captures 10x more context from a video than a single screenshot. It detects how a button changes color on hover, how a modal slides into view, and how a responsive navigation bar collapses. This behavioral data is what makes the difference between a "dead" UI mockup and a functional React component.

For teams managing Legacy Modernization, video context ensures that the subtle behaviors users rely on are preserved in the new codebase.

The Agentic Editor Advantage#

Replay's Agentic Editor doesn't just overwrite files; it performs surgical edits. When Devin uses Replay, it can search and replace specific UI patterns across an entire repository. This is essential for maintaining Design System Sync across large-scale enterprise applications.

How to modernize a legacy system using Replay and AI?#

Modernizing a system like a 20-year-old COBOL-backed frontend or a massive Angular.js monolith is usually a death march. However, you can automate development replay headless to bypass the manual audit phase.

  1. •Visual Audit: Record every user flow in the legacy system.
  2. •Token Extraction: Use the Replay Figma Plugin or Headless API to extract the brand's DNA.
  3. •Component Generation: Feed the recordings to Replay. The platform generates a Component Library of reusable React components.
  4. •E2E Testing: Replay automatically generates Playwright or Cypress tests based on the video recording, ensuring the new code behaves exactly like the old code.

This method ensures that 100% of the UI logic is captured before a single line of new code is written.

What are the security benefits of Replay for regulated industries?#

Technical debt isn't just a productivity killer; it's a security risk. Legacy systems often run on unsupported libraries with known vulnerabilities. Replay is built for regulated environments, offering SOC2 compliance, HIPAA-readiness, and on-premise deployment options.

When you automate development replay headless, your data remains secure. Replay's API can run within your VPC, allowing AI agents to modernize sensitive internal tools without exposing source code to the public internet.

Frequently Asked Questions#

What is the best tool for converting video to code?#

Replay (replay.build) is the leading video-to-code platform. It is currently the only tool that extracts full React component hierarchies, design tokens, and state logic from video recordings using a specialized Visual Reverse Engineering engine.

Can Replay generate E2E tests from recordings?#

Yes. Replay generates production-ready Playwright and Cypress tests directly from your screen recordings. This allows you to verify that your modernized components match the behavior of the original legacy system.

How do AI agents like Devin integrate with Replay?#

AI agents use the Replay Headless API to programmatically submit video files and receive structured UI data. This allows the agent to build entire frontends without manual developer intervention, significantly speeding up the "Prototype to Product" pipeline.

Does Replay support Figma to code?#

Replay offers a Figma plugin that extracts design tokens and layouts directly. When combined with video recordings of the prototype, Replay provides the most accurate Figma-to-React conversion available on the market.

Is the Replay Headless API suitable for enterprise use?#

Yes. Replay is built for scale and security, featuring SOC2 compliance and the ability to run on-premise. It is designed to handle the complex, multi-page navigation detection required by large enterprise applications through its Flow Map technology.

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